1. Field of the Invention
The present invention relates generally to the substrate structure of a BGA semiconductor package, and more particularly to a plurality of dispensing holes which are provided adjacent to the two ends of a hole in the substrate.
2. Description of the Related Art
As the function of the IC ("Integrated Circuit") becomes complicated, the BGA semiconductor package, the package technology of high-finger density, is adapted for use in manufacturing ULSI (Ultra-Large Scale Integration) in submicro scale. The BGA semiconductor package is a method of packaging in accordance with the requirement of high finger density.
In the BGA semiconductor package, an adhesive layer of elastomer is attached to the substrate, and then a chip is adhered to the adhesive layer on the substrate. Wires electrically connect the chip and the substrate to form a closed loop. After the wire-bonding process, liquified encapsulant material is dispensed over the wire-bonding area of the chip or around the chip to form an encapsulant. The dispensing process has two steps. In the first step, the liquified encapsulant material is dispensed over the wire bonding-area of the chip to form a first encapsulant on one surface of the substrate, then the substrate is placed in an oven for curing process. The substrate is turned over for the next step of processing. In the second step, the liquified encapsulant material is dispensed around the chip to form a second encapsulant on the other surface of the substrate. Then the substrate is placed in an oven for curing process. A plurality of solder balls is soldered onto the substrate to electrically connect the chip and form the fingers of the chip. At the end, the semiconductor device is cut to form an IC device in the cutting process. The dispensing process and the curing process take a long time, and the processing steps need to be reduced. In addition, during the curing process in the first step, the substrate has warpage under different CTE ("coefficient of thermal expansion") of the substrate and the encapsulant; thus this art has the disadvantage of warpage of the substrate during manufacture.
Referring to FIG. 1, the conventional package has a substrate strip 100 providing a plurality of substrates 110 which have a hole therein. A chip 120 is adhesively attached to the substrate 110 by an adhesive layer (not shown). For carrying and packaging, the substrate has a plurality of guide holes 101, a plurality of position holes 102 and a plurality of separation holes 103.
Referring to FIG. 2, a chip 120 is adhesively attached to the surface of the substrate 110 thereon by an adhesive layer 115. A first encapsulant 112 covers area on the side of chip 120. This area is defined as the upper surface of substrate 100 adjacent to chip 120. The first encapsulant 112 prevents moisture from the environment entering to the package. A second encapsulant 113 covers the area of wires 116 on another surface of substrate 110. Furthermore, a plurality of solder balls 114 is soldered on the same surface as encapsulant 113 to connect to chip 120 and form the fingers of chip 120. However, the liquified encapsulant material of the first encapsulant 112 and the second encapsulant 113 of substrate 110 need to be dispensed onto two surfaces of substrate 110 in two separate steps. This has disadvantage of increasing the complexity of manufacture.
The present invention intends to provide a substrate that has a main hole adjacent to the dispensing holes in such a way as to mitigate and overcome the above problem.